A device is provided to facilitate introduction of a fluid agent (such as a deicing agent) into the air line of a trailer of a tractor trailer. The device comprises a canister defining an upwardly opening chamber, a lid removably securable to the canister to close the chamber, an inlet tube extending from the canister and having a connector at an end of the inlet tube, a valve in said inlet tube; and an outlet tube extending from the canister and having a connector at an end of the inlet tube. The outlet tube is shaped and sized such that the canister chamber can be filled with the liquid agent from the ground and without the need to climb on the chassis of the trailer tractor.